#include <stdio.h>
int main(int argc, char const *argv[])
{
    char str1[20] = {0};
    char str2[20] = {0};
    printf("请输入第一个字符串>:");
    scanf("%s", str1);
    printf("请输入第二个字符串>:");
    scanf("%s", str2);
    printf("str1=%s\n", str1);
    printf("str2=%s\n", str2);
    int len = 0;
    while (str1[len] != '\0')
        len++;
    printf("len=%d\n", len);
    for (int i = 0; str2[i] != '\0'; i++)
    {
        str1[len] = str2[i];
        len++;
    }
    printf("str1=%s", str1);

    return 0;
}
